This invention relates to the art of making electron emission surfaces and more particularly to multialkali activation or sensitization or methods applicable to such surfaces.
Methods of sensitizing electron emissive surfaces of, for example, supported base layers of antimony are well known in the art of electron discharge devices. Such methods generally relate to the sensitization of either photocathodes or secondary emissive electrodes. Photoemissive materials and techniques relating thereto are, for example, described in Photoemissive Materials by A. H. Sommer, John Wiley and Sons, Inc., New York, 1968 and is herein incorporated by reference. Unfortunately, while various methods or techniques may be effectively employed to maximally sensitize one or the other of these types of electron emissive electrodes, individually, no one method has been found which permits the multialkali sensitization of both photosensitive and secondary emissive type electrodes simultaneously within the same processing apparatus without substantially impairing the achievable performance characteristics of one or the other of the types of electrodes.
In the manufacture of photomultipliers, it is highly desirable to simultaneously sensitize both a multialkali type photocathode and a plurality of dynode or secondary emissive electrodes subsequent to their assembly within a common tubular envelope. In general, selection of any of the known prior art sensitization schedules, suitable for maximizing the sensitivity of the photocathode, results in the simultaneous formation of an inferior secondary emissive dynode, electrode, or vice versa.
A compatible method suitable for sensitizing photoemissive and secondary emissive type electrode surfaces simultaneously in the same processing apparatus is highly desired whereby improved overall response characteristics may be achieved for devices employing both types of electrodes.